DISEASES OF THE NERVOUS SYSTEM 63 



rhachitis, when the thigh-bones become fractured, 

 and is caused by feeding a ration deficient in mineral 

 matter. It is frequently caused by small centers of 

 inflammation in the spinal cord resulting from disease 

 or an injury to the back, pressure on the cord from 

 tumors, or an over-fat condition, and the encysting of 

 parasites in this part of the nervous system. It is 

 not uncommon for hogs that have been shipped in 

 cars and crates to be affected in this way. Loss of 

 control over the movement of the hirid parts and 

 other nervous disturbances sometimes occur in sows 

 that are nursing a litter of pigs and are run down in 

 condition. Injuries caused by the hogs piling on one 

 another, indigestion, and constipation are said to 

 cause this disease. 



Symptoms. — The paralysis may come on grad- 

 ually, and nearly always involves both hind limbs. In 

 case the disease develops slowly, the first symptoms 

 noticed is an unsteady gait, the hind legs not follow- 

 ing in an exact line with the front ones, and, instead 

 of walking directly forward, the hog appears to move 

 sideways. Sometimes, the legs become crossed, and 

 the animal may take this position when standing. 

 After lying down there is more or less difficulty in 

 getting up. These symptoms become progressively 

 worse until the hog simply drags the hind parts, and 

 is unable to get up or support its weight on the hind 

 feet. 



The appetite is usually good in the early stage and 

 may remain so. ^ Pressure over the back and loins 

 does not cause the animal pain, but it may squeal 



